* {font-family: "Microsoft Yahei", "Arial"; margin: 0; padding: 0; border: none;  }
body { font-size: .7vw; background: #eee; }

nav {display: grid;  border-bottom: 1px solid #696969; background: #fff; grid-template-columns: repeat(4, 150px); grid-template-rows: 50px; justify-items: center; align-items: center; justify-content: space-evenly; }
nav dd {font-size: 1.2rem;line-height: 1.6rem;  display: none; background: #fff;  }
nav dt,
nav dd { cursor: pointer; }
nav > dl { position: relative; }
nav > dl > dt { font-size: 1.4rem; }
nav > dl > dd { position: absolute; }
nav > dl:hover > dd { display: block; }
nav > dl > dd > dl > dd { margin-left: 20px; }
nav > dl > dd > dl:hover > dd { display: block; }
